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Diffstat (limited to 'libevent/evbuffer-internal.h')
| -rw-r--r-- | libevent/evbuffer-internal.h | 351 |
1 files changed, 351 insertions, 0 deletions
diff --git a/libevent/evbuffer-internal.h b/libevent/evbuffer-internal.h new file mode 100644 index 0000000..d09b4f1 --- /dev/null +++ b/libevent/evbuffer-internal.h @@ -0,0 +1,351 @@ +/* + * Copyright (c) 2000-2007 Niels Provos <provos@citi.umich.edu> + * Copyright (c) 2007-2012 Niels Provos and Nick Mathewson + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. The name of the author may not be used to endorse or promote products + * derived from this software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR + * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES + * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. + * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT + * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF + * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + */ +#ifndef EVBUFFER_INTERNAL_H_INCLUDED_ +#define EVBUFFER_INTERNAL_H_INCLUDED_ + +#ifdef __cplusplus +extern "C" { +#endif + +#include "event2/event-config.h" +#include "evconfig-private.h" +#include "event2/util.h" +#include "event2/event_struct.h" +#include "util-internal.h" +#include "defer-internal.h" + +/* Experimental cb flag: "never deferred." Implementation note: + * these callbacks may get an inaccurate view of n_del/n_added in their + * arguments. */ +#define EVBUFFER_CB_NODEFER 2 + +#ifdef _WIN32 +#include <winsock2.h> +#endif +#include <sys/queue.h> + +/* Minimum allocation for a chain. We define this so that we're burning no + * more than 5% of each allocation on overhead. It would be nice to lose even + * less space, though. */ +#if EVENT__SIZEOF_VOID_P < 8 +#define MIN_BUFFER_SIZE 512 +#else +#define MIN_BUFFER_SIZE 1024 +#endif + +/** A single evbuffer callback for an evbuffer. This function will be invoked + * when bytes are added to or removed from the evbuffer. */ +struct evbuffer_cb_entry { + /** Structures to implement a doubly-linked queue of callbacks */ + LIST_ENTRY(evbuffer_cb_entry) next; + /** The callback function to invoke when this callback is called. + If EVBUFFER_CB_OBSOLETE is set in flags, the cb_obsolete field is + valid; otherwise, cb_func is valid. */ + union { + evbuffer_cb_func cb_func; + evbuffer_cb cb_obsolete; + } cb; + /** Argument to pass to cb. */ + void *cbarg; + /** Currently set flags on this callback. */ + ev_uint32_t flags; +}; + +struct bufferevent; +struct evbuffer_chain; +struct evbuffer { + /** The first chain in this buffer's linked list of chains. */ + struct evbuffer_chain *first; + /** The last chain in this buffer's linked list of chains. */ + struct evbuffer_chain *last; + + /** Pointer to the next pointer pointing at the 'last_with_data' chain. + * + * To unpack: + * + * The last_with_data chain is the last chain that has any data in it. + * If all chains in the buffer are empty, it is the first chain. + * If the buffer has no chains, it is NULL. + * + * The last_with_datap pointer points at _whatever 'next' pointer_ + * pointing at the last_with_data chain. If the last_with_data chain + * is the first chain, or it is NULL, then the last_with_datap pointer + * is &buf->first. + */ + struct evbuffer_chain **last_with_datap; + + /** Total amount of bytes stored in all chains.*/ + size_t total_len; + + /** Number of bytes we have added to the buffer since we last tried to + * invoke callbacks. */ + size_t n_add_for_cb; + /** Number of bytes we have removed from the buffer since we last + * tried to invoke callbacks. */ + size_t n_del_for_cb; + +#ifndef EVENT__DISABLE_THREAD_SUPPORT + /** A lock used to mediate access to this buffer. */ + void *lock; +#endif + /** True iff we should free the lock field when we free this + * evbuffer. */ + unsigned own_lock : 1; + /** True iff we should not allow changes to the front of the buffer + * (drains or prepends). */ + unsigned freeze_start : 1; + /** True iff we should not allow changes to the end of the buffer + * (appends) */ + unsigned freeze_end : 1; + /** True iff this evbuffer's callbacks are not invoked immediately + * upon a change in the buffer, but instead are deferred to be invoked + * from the event_base's loop. Useful for preventing enormous stack + * overflows when we have mutually recursive callbacks, and for + * serializing callbacks in a single thread. */ + unsigned deferred_cbs : 1; +#ifdef _WIN32 + /** True iff this buffer is set up for overlapped IO. */ + unsigned is_overlapped : 1; +#endif + /** Zero or more EVBUFFER_FLAG_* bits */ + ev_uint32_t flags; + + /** Used to implement deferred callbacks. */ + struct event_base *cb_queue; + + /** A reference count on this evbuffer. When the reference count + * reaches 0, the buffer is destroyed. Manipulated with + * evbuffer_incref and evbuffer_decref_and_unlock and + * evbuffer_free. */ + int refcnt; + + /** A struct event_callback handle to make all of this buffer's callbacks + * invoked from the event loop. */ + struct event_callback deferred; + + /** A doubly-linked-list of callback functions */ + LIST_HEAD(evbuffer_cb_queue, evbuffer_cb_entry) callbacks; + + /** The parent bufferevent object this evbuffer belongs to. + * NULL if the evbuffer stands alone. */ + struct bufferevent *parent; +}; + +#if EVENT__SIZEOF_OFF_T < EVENT__SIZEOF_SIZE_T +typedef ev_ssize_t ev_misalign_t; +#define EVBUFFER_CHAIN_MAX ((size_t)EV_SSIZE_MAX) +#else +typedef ev_off_t ev_misalign_t; +#if EVENT__SIZEOF_OFF_T > EVENT__SIZEOF_SIZE_T +#define EVBUFFER_CHAIN_MAX EV_SIZE_MAX +#else +#define EVBUFFER_CHAIN_MAX ((size_t)EV_SSIZE_MAX) +#endif +#endif + +/** A single item in an evbuffer. */ +struct evbuffer_chain { + /** points to next buffer in the chain */ + struct evbuffer_chain *next; + + /** total allocation available in the buffer field. */ + size_t buffer_len; + + /** unused space at the beginning of buffer or an offset into a + * file for sendfile buffers. */ + ev_misalign_t misalign; + + /** Offset into buffer + misalign at which to start writing. + * In other words, the total number of bytes actually stored + * in buffer. */ + size_t off; + + /** Set if special handling is required for this chain */ + unsigned flags; +#define EVBUFFER_FILESEGMENT 0x0001 /**< A chain used for a file segment */ +#define EVBUFFER_SENDFILE 0x0002 /**< a chain used with sendfile */ +#define EVBUFFER_REFERENCE 0x0004 /**< a chain with a mem reference */ +#define EVBUFFER_IMMUTABLE 0x0008 /**< read-only chain */ + /** a chain that mustn't be reallocated or freed, or have its contents + * memmoved, until the chain is un-pinned. */ +#define EVBUFFER_MEM_PINNED_R 0x0010 +#define EVBUFFER_MEM_PINNED_W 0x0020 +#define EVBUFFER_MEM_PINNED_ANY (EVBUFFER_MEM_PINNED_R|EVBUFFER_MEM_PINNED_W) + /** a chain that should be freed, but can't be freed until it is + * un-pinned. */ +#define EVBUFFER_DANGLING 0x0040 + /** a chain that is a referenced copy of another chain */ +#define EVBUFFER_MULTICAST 0x0080 + + /** number of references to this chain */ + int refcnt; + + /** Usually points to the read-write memory belonging to this + * buffer allocated as part of the evbuffer_chain allocation. + * For mmap, this can be a read-only buffer and + * EVBUFFER_IMMUTABLE will be set in flags. For sendfile, it + * may point to NULL. + */ + unsigned char *buffer; +}; + +/** callback for a reference chain; lets us know what to do with it when + * we're done with it. Lives at the end of an evbuffer_chain with the + * EVBUFFER_REFERENCE flag set */ +struct evbuffer_chain_reference { + evbuffer_ref_cleanup_cb cleanupfn; + void *extra; +}; + +/** File segment for a file-segment chain. Lives at the end of an + * evbuffer_chain with the EVBUFFER_FILESEGMENT flag set. */ +struct evbuffer_chain_file_segment { + struct evbuffer_file_segment *segment; +#ifdef _WIN32 + /** If we're using CreateFileMapping, this is the handle to the view. */ + HANDLE view_handle; +#endif +}; + +/* Declared in event2/buffer.h; defined here. */ +struct evbuffer_file_segment { + void *lock; /**< lock prevent concurrent access to refcnt */ + int refcnt; /**< Reference count for this file segment */ + unsigned flags; /**< combination of EVBUF_FS_* flags */ + + /** What kind of file segment is this? */ + unsigned can_sendfile : 1; + unsigned is_mapping : 1; + + /** The fd that we read the data from. */ + int fd; + /** If we're using mmap, this is the raw mapped memory. */ + void *mapping; +#ifdef _WIN32 + /** If we're using CreateFileMapping, this is the mapping */ + HANDLE mapping_handle; +#endif + /** If we're using mmap or IO, this is the content of the file + * segment. */ + char *contents; + /** Position of this segment within the file. */ + ev_off_t file_offset; + /** If we're using mmap, this is the offset within 'mapping' where + * this data segment begins. */ + ev_off_t mmap_offset; + /** The length of this segment. */ + ev_off_t length; + /** Cleanup callback function */ + evbuffer_file_segment_cleanup_cb cleanup_cb; + /** Argument to be pass to cleanup callback function */ + void *cleanup_cb_arg; +}; + +/** Information about the multicast parent of a chain. Lives at the + * end of an evbuffer_chain with the EVBUFFER_MULTICAST flag set. */ +struct evbuffer_multicast_parent { + /** source buffer the multicast parent belongs to */ + struct evbuffer *source; + /** multicast parent for this chain */ + struct evbuffer_chain *parent; +}; + +#define EVBUFFER_CHAIN_SIZE sizeof(struct evbuffer_chain) +/** Return a pointer to extra data allocated along with an evbuffer. */ +#define EVBUFFER_CHAIN_EXTRA(t, c) (t *)((struct evbuffer_chain *)(c) + 1) + +/** Assert that we are holding the lock on an evbuffer */ +#define ASSERT_EVBUFFER_LOCKED(buffer) \ + EVLOCK_ASSERT_LOCKED((buffer)->lock) + +#define EVBUFFER_LOCK(buffer) \ + do { \ + EVLOCK_LOCK((buffer)->lock, 0); \ + } while (0) +#define EVBUFFER_UNLOCK(buffer) \ + do { \ + EVLOCK_UNLOCK((buffer)->lock, 0); \ + } while (0) +#define EVBUFFER_LOCK2(buffer1, buffer2) \ + do { \ + EVLOCK_LOCK2((buffer1)->lock, (buffer2)->lock, 0, 0); \ + } while (0) +#define EVBUFFER_UNLOCK2(buffer1, buffer2) \ + do { \ + EVLOCK_UNLOCK2((buffer1)->lock, (buffer2)->lock, 0, 0); \ + } while (0) + +/** Increase the reference count of buf by one. */ +void evbuffer_incref_(struct evbuffer *buf); +/** Increase the reference count of buf by one and acquire the lock. */ +void evbuffer_incref_and_lock_(struct evbuffer *buf); +/** Pin a single buffer chain using a given flag. A pinned chunk may not be + * moved or freed until it is unpinned. */ +void evbuffer_chain_pin_(struct evbuffer_chain *chain, unsigned flag); +/** Unpin a single buffer chain using a given flag. */ +void evbuffer_chain_unpin_(struct evbuffer_chain *chain, unsigned flag); +/** As evbuffer_free, but requires that we hold a lock on the buffer, and + * releases the lock before freeing it and the buffer. */ +void evbuffer_decref_and_unlock_(struct evbuffer *buffer); + +/** As evbuffer_expand, but does not guarantee that the newly allocated memory + * is contiguous. Instead, it may be split across two or more chunks. */ +int evbuffer_expand_fast_(struct evbuffer *, size_t, int); + +/** Helper: prepares for a readv/WSARecv call by expanding the buffer to + * hold enough memory to read 'howmuch' bytes in possibly noncontiguous memory. + * Sets up the one or two iovecs in 'vecs' to point to the free memory and its + * extent, and *chainp to point to the first chain that we'll try to read into. + * Returns the number of vecs used. + */ +int evbuffer_read_setup_vecs_(struct evbuffer *buf, ev_ssize_t howmuch, + struct evbuffer_iovec *vecs, int n_vecs, struct evbuffer_chain ***chainp, + int exact); + +/* Helper macro: copies an evbuffer_iovec in ei to a win32 WSABUF in i. */ +#define WSABUF_FROM_EVBUFFER_IOV(i,ei) do { \ + (i)->buf = (ei)->iov_base; \ + (i)->len = (unsigned long)(ei)->iov_len; \ + } while (0) +/* XXXX the cast above is safe for now, but not if we allow mmaps on win64. + * See note in buffer_iocp's launch_write function */ + +/** Set the parent bufferevent object for buf to bev */ +void evbuffer_set_parent_(struct evbuffer *buf, struct bufferevent *bev); + +void evbuffer_invoke_callbacks_(struct evbuffer *buf); + + +int evbuffer_get_callbacks_(struct evbuffer *buffer, + struct event_callback **cbs, + int max_cbs); + +#ifdef __cplusplus +} +#endif + +#endif /* EVBUFFER_INTERNAL_H_INCLUDED_ */ |